Field
Aspects of the present invention generally relate to an electrophotographic photosensitive member and, in addition, a process cartridge and an electrophotographic apparatus which include the electrophotographic photosensitive member.
Description of the Related Art
An electrophotographic photosensitive member is mounted on a process cartridge or an electrophotographic apparatus and a charging device, an exposure device, a developing device, a transfer device, a cleaning device, and the like are provided around the electrophotographic photosensitive member. In an electrophotographic apparatus, image forming is performed through the steps by using these devices. The electrophotographic photosensitive member undergoes slide-rubbing and contact pressure with these devices and members around them and damage and abrasion occur easily.
In recent years, higher speed, long lifetime process cartridges and electrophotographic apparatuses have been required, and improvement in the long-term durability of the electrophotographic photosensitive member has been desired. Along with increases in speed and lifetime, damage and abrasion due to slide-rubbing and a contact pressure (contact force) between the charge transporting layer of the electrophotographic photosensitive member and the member which comes into contact therewith increase, so that more improvement in the durability of the charge transporting layer is desired. In particular, an influence on the electrophotographic photosensitive member exerted by application of the contact pressure (contact force) from a gap retaining member configured to retain (regulate) a distance between the electrophotographic photosensitive member and a charging member or a developer bearing member is large, and the charge transporting layer of the electrophotographic photosensitive member may be peeled in long-term repetitive use.
In the electrophotographic photosensitive member, in many cases, an undercoat layer is disposed to control movement of charges from a support to a photosensitive layer and enhance the adhesive force between the support and the photosensitive layer. However, even in the case where the undercoat layer is disposed, there is a problem that the photosensitive layer is peeled easily in a region (non-image forming region) of the electrophotographic photosensitive member which comes into contact with the gap retaining member. Then, Japanese Patent Laid-Open No. 59-184359 describes a technology in which an end portion of the photosensitive layer is formed inside an end portion of the undercoat layer.
Also, Japanese Patent Laid-Open No. 2002-107986 describes a technology in which a photosensitive layer is formed in such a way as to cover an undercoat layer containing a metal oxide particle, suppress flaking of the metal oxide particle on the surface of the undercoat layer, and suppress soiling of the surface layer of the electrophotographic photosensitive member.
As a result of studies conducted by the present inventors, it was found that in the case where a charge transporting layer serving as a surface layer was formed on an undercoat layer containing a phenol resin and a metal oxide particle, referring to the technology described in Japanese Patent Laid-Open No. 2002-107986, a surface layer peeling problem was not always improved. In particular, the charge transporting layer in the region which came into contact with the gap retaining member was peeled easily. In addition, it was found that peeling of the charge transporting layer occurred more easily in a low-temperature, low-humidity environment and there was room for further improvement.